1. Field of the Invention
The present general inventive concept relates to an ink-jet print head, and more particularly, to a thermal transfer type ink-jet print head having a protective layer to protect a heat generation layer, and a method of fabricating the same.
2. Description of the Related Art
Conventionally, an ink-jet print head may be classified into a piezoelectric type, which ejects ink using a piezoelectric member, and a heat transfer type, which ejects ink using bubbles generated when the ink is instantly heated by a heat generation member.
FIG. 1 illustrates a conventional heat transfer type ink-jet print head.
Referring to FIG. 1, a conventional ink-jet print head 100 includes substrate 110, an insulating layer 120, a heat generation layer 130, an electrode layer 140, a protective layer 150, a chamber layer 180, and a nozzle layer 190 having a nozzle 195. The heat generation layer 130 functions to instantly heat ink filled in an ink chamber 115, and the electrode layer 140 functions to apply electric power to the heat generation layer 130.
The protective layer 150 functions to protect the heat generation layer 130. The conventional protective layer 150 includes a first protective layer 160 and a second protective layer 170 sequentially laminated on top surfaces of the heat generation layer 130 and the electrode layer 140, as disclosed in U.S. Pat. No. 4,335,389. The second protective layer 170 functions to prevent a failure of the heat generation layer 130, which is caused by a cavitation force generated when bubbles formed within the ink chamber 115 are contracted after the ink is ejected. In general, the second protective layer 170 is formed by depositing tantalum (Ta) or tantalum nitride (TaNx) on the top surface of the first protective layer 160.
In addition, the first protective layer 160 functions to electrically insulate the heat generation layer 130 and the electrode layer 140, and is formed by depositing silicon oxide (SiOx) or silicon nitride (SiNx) on the top surfaces of the heat generation layer 130 and the electrode layer 140. Conventionally, the SiNx layer is deposited through a plasma enhanced chemical vapor deposition (PECVD) process, and the thickness of the single SiNx deposited is about 6,000 Å.
However, the conventional first protective layer 160 formed as described above has defects, such as fine holes usually called “pinholes,” formed at the time of forming the protective layers. In particular, these pinholes are inevitably formed due to characteristics of the conventional process of forming such a protective layer and a material thereof. When the ink-jet print head 100 is operated for an extended period of time, the above-mentioned pinholes principally contribute to cause a failure of the first protective layer 160 due to the cavitation force. Such a failure of the first protective layer 160 is more frequently produced at an area C where the heat generation layer 130 and the electrode layer 140 are joined to one another forming a step being between them. For example, a portion including the pinholes has a poor mechanical rigidity, and may act as a point at which cracks occur when the cavitation force is exerted. As such, if the first protective layer 160 suffers a failure, the heat generation layer 130 may also suffer a failure by the cavitation force. In addition, the heat generation layer 130 may be electrically shorted with the second protective layer 170 or the ink may contact the heat generation layer 130 through a damaged part of the first protective layer 160. As a result, a duration and/or quality of the ink-jet print head will be deteriorated and defects (pinholes) in the first protective layer 160 are closely associated with the duration of the heat generation layer 130.